Simplicillium ovoideum Yao Wang & Hui Chen 2026, sp. nov.

Simplicillium ovoideum Yao Wang & Hui Chen sp. nov. Fig. 4 Etymology. The epithet ovoideum refers to the ovoid to elongated-ovoid conidia of the species. Type. China • Yunnan Province, Xishuangbanna Dai Autonomous Prefecture, Mengla County, Mohan Town (21°12'N, 101°44'E, 1080 m above sea level), isolated from soil, August 2024, Yao Wang (holotype, dried culture: GMB 3235; ex-holotype living culture: GMBC 3235). Description. Sexual morph. Undetermined. Asexual morph. Hyphomycetous. Mycelium hyaline, smooth-walled, sparsely septate. Phialides 17.3–52.2 × 1.1–1.8 μm (x ̄ = 28 × 1.5 μm, n = 30), arising from procumbent hyphae or synnemata, blastic, enteroblastic, phialidic, monophialidic, discrete, terminal, unbranched, solitary, aseptate, hyaline, smooth-walled, slender, occasionally with a swollen node. Conidia 2.8–4.1 × 1.7–2.5 μm (x ̄ = 3.6 × 2.0 μm, n = 30), ovoid to elongated-ovoid, hyaline, aseptate, smooth-walled, aggregated in conidial heads at the tips of phialides. Culture characteristics. Colonies on PDA attaining a diameter of 4.2–4.7 cm (x ̄ = 4.5 cm, n = 10) after 14 days at 25 ° C, circular with entire margins, white and velvety on the surface, with a depressed center; reverse creamy white to pale yellow, flat. Substrate. Soil and the rust fungus Hemileia vastatrix (fungicolous). Habitat and distribution. Known from soil in China (Yunnan Province) and Laos (Oudomxay Province), at elevations of 760–1080 m above sea level, and associated with Hemileia vastatrix in Jamaica. Additional material examined. Laos • Oudomxay Province, Nam Kat Yorla Pa Resort (20°41'N, 101°59'E, 760 m above sea level), isolated from soil, August 2024, Yao Wang (GMB 3236; living culture: GMBC 3236); Jamaica, on Hemileia vastatrix, September 1998, H. C. Evans (IMI 317442; living culture: CBS 101267). Notes. Morphologically, S. ovoideum is readily distinguished from S. pseudocercosporicola by its ovoid to elongated-ovoid conidia (vs. subcylindrical) (Custódio and Pereira 2025, Table 3). Ecologically, the two species differ in substrate association: S. ovoideum occurs in soil and as a mycoparasite of Hemileia vastatrix, whereas S. pseudocercosporicola is fungicolous on Pseudocercospora fijiensis (Custódio and Pereira 2025). Notably, the historically misidentified strain CBS 101267, widely cited as S. lanosoniveum in phylogenetic studies of Cordycipitaceae, is nested within the S. ovoideum clade and clearly distant from the ex-type strain of S. lanosoniveum (CBS 123.42), prompting its formal reassignment to S. ovoideum. This correction underscores the necessity of re-evaluating historically annotated reference strains using robust multilocus data, especially in morphologically cryptic species complexes. The independent phylogenetic position, distinctive conidial morphology, and ecological niche differentiation support S. ovoideum as a distinct novel species.